1. Field of the Invention
The present invention relates to a system for detection of a surgical implement; and more particularly, to a system wherein a magnetomechanically resonant marker is attached to a surgical implement, thereby permitting the implement to be detected if inadvertently left within a patient during a surgical procedure.
2. Description of the Prior Art
During the course of a surgical operation it is generally necessary for a variety of articles, such as surgical sponges, gauzes, instruments and the like, to be placed into a wound cavity. Despite rigorous attention given to locating these items and ensuring removal of all of them prior to completion of the surgical procedure and closure of the surgical incision, such items are sometimes overlooked and remain within the patient. When this occurs, serious consequences often ensue. The patient may suffer pain, infection, intestinal obstruction, and even death. An additional invasive surgical procedure to remove the foreign object is essential to prevent serious, and possibly fatal, consequences to the patient. The severity of the problem of retained surgical implements has been recognized since the earliest days of surgery. The procedures traditionally employed to prevent post-surgical implement retention include manual search of the wound by the surgeon prior to closure and a careful accounting for all materials inserted and removed from the wound. This accounting function is customarily carried out by the operating room staff, usually the circulating nurse. Notwithstanding these precautionary measures the accidental retention of surgical implements continues to occur to this day with disturbing regularity, even in highly respected institutions. Surgeons and related medical professionals regard this eventuality as a major unsolved problem.
At present, physical count combined with manual search remains the primary protocol used for detecting retained surgical implements. Nevertheless, the above-mentioned shortcomings of the protocol have led to other approaches, such as the use of x-ray methods. Most surgical instruments are composed of metal, and are easily visible on x-ray. Sponges are generally made to bear a radiopaque component to make them also visible on x-ray. However, intraoperative x-rays are not routinely performed before closure of the incision for several reasons: They entail the risk of extension of operative time and anesthesia, along with undesirable expense, inconvenience, and radiation exposure. Postoperative x-rays are subject to some of the same disadvantages and are not routinely done unless there is a specific question or suspicion of a retained implement in a given case. Moreover, even when postoperative x-rays are obtained, retained surgical implements are still overlooked in many cases, owing to the presence of artifacts or other competing shadows on the film or the unfavorable orientation of the object relative to the direction of the incident x-ray beam and the position of the x-ray film. If a retained article is detected, a timely second operation is required to effect its removal, notwithstanding the further trauma to the patient. The severity of the problem clearly warrants efforts that allow the aforementioned consequences to be avoided altogether by ensuring removal of the offending articles before surgery is completed, not at a later point.
The problem of retained sponges is particularly severe. After use, a sponge is generally soaked with blood or other bodily fluids, making it difficult for the surgeon to spot against the background of the fluids and body structures within the surgical cavity. Surgical sponges about 45 cm (18 inches) square are used in virtually all major abdominal surgeries, and are the surgical item most frequently overlooked. Accordingly, a single method and system by which this and other surgical items can be reliably detected in a surgical cavity would afford a significant improvement in the safety of surgery.
Over the years many efforts have been made to prevent the accidental retention of surgical implements. U.S. Pat. Nos. 5,057,095, 5,107,862, 5,190,059, 5,329,944, 5,105,829, and 5,188,126 to Fabian et al. disclose the use of various technologies to detect surgical implements marked with a tag and left within the surgical wound after completion of surgery and prior to closing the wound. Despite these and other disclosures, the use of externally detectable markers has not yet become a part of routine hospital practice. Among the remaining impediments are the size and physical characteristics of known marker tags to which present detection systems are reliably responsive.
Suitable systems and the associated markers must satisfy a number of requirements. There must be reliable and convenient means of affixing such markers to surgical items. Any item used invasively must be capable of being appropriately sanitized and sterilized prior to use. The size and physical characteristics of the attached tag must not compromise the functionality of the surgical item or unduly restrict the ability of the surgeon or other assistant to see and access the operation site and to manipulate and use the item in an optimal manner for its intended primary function. The item should not harm the patient and should be compatible with the surgical environment and not be degraded in the presence of bodily fluids and other substances encountered during surgery.
The markers required for presently available surgical implement detection systems are of a size that precludes their attachment to many commonly used implements. Systems employing markers that are smaller and lighter, without a concomitant reduction in the detectability of marked, retained instruments are thus highly sought.